1. Field of the Invention
The present invention relates to storage and dispensing vessels such as are utilized for storage, transport and dispensing of materials in semiconductor manufacturing operations. More specifically, the invention relates to a secondary package for storage and dispensing vessels as well as to a method of making vessels having a secondary package.
2. Description of the Related Art
Vessels of widely varying types are extensively utilized in chemical industries, including semiconductor manufacturing, where liquid containers, gas cylinders and other types of material packages are used to supply reagents such as hydrides, halides, organometallic compounds, etc. to semiconductor manufacturing tools.
In the field of semiconductor manufacturing, new packaging approaches have been developed in recent years, including low pressure adsorbent-based fluid storage and dispensing vessels of the type disclosed in Tom et al. U.S. Pat. No. 5,518,528, as commercially available from ATMI, Inc. (Danbury, Conn.) under the trademark “SDS,” and pressure-regulated fluid storage and dispensing vessels of the type described in Wang et al. U.S. Pat. No. 6,101,816, Wang et al. U.S. Pat. No. 6,089,027 and Wang et al. U.S. Pat. No. 6,343,476, as commercially available from ATMI, Inc. (Danbury, Conn.) under the trademark “VAC.” Regardless of the specific type of material storage and dispensing vessel employed in a given material-consuming operation, it is necessary to maintain complete structural integrity in the storage, transport and deployment of such vessels, so that no leakage of contained material takes place, such as by leakage through couplings, valve head fittings, burst disks or other pressure relief devices associated with the vessel, seams, ports or other joints where welds or bonding media may fail and result in release of material from the vessel, etc.
The foregoing considerations are particularly acute where the contained material is very expensive, as in the microelectronics industry, where chemical reagents must be in many cases >99.999% pure in order to achieve reliability and acceptability of the product integrated circuitry that is manufactured using such chemical reagents. The foregoing also applies where the contained material is toxic or hazardous in character, and leakage may compromise human health and safety, or otherwise produce injury or adverse impact on the environment, or to the process facility in which the material is to be utilized.
For these reasons, it is common practice in the field of industrial containment to subject storage and dispensing vessels to leak-testing procedures, e.g., at the time that they are filled with material and sealed to provide the product package of material for subsequent use.
Although such point-of-origin testing of the leak-tightness of the storage and dispensing vessel may be effective to detect so-called “leakers,” which then can be isolated and reworked or otherwise appropriately processed, there remains the potential during subsequent transport, storage and installation, for damage to occur to the vessel, that may compromise its structural integrity and leak-tightness.
For example, conventional gas cylinders are typically transported in bulk arrays that are strapped or secured together for transportation by truck, railcar, etc. In this condition, the vessels are subjected to shock, vibration, and impact, during their transport any intervening storage and final installation. Additionally, differential thermal effects may be significant, such as where such gas cylinders are transported by truck or railcar in long-haul operations, during which variations of temperature and humidity may adversely affect the structural integrity of the vessel and mediate leakage of fluid from the compromised vessel.
The foregoing potential for leakage is ameliorated to some extent by low-pressure packaging and dispensing of fluids, such as in the aforementioned SDS® and VAC® vessels, but nonetheless remains a significant risk in the transport, storage and installation of such vessels. It would therefore be a substantial advance in the art to markedly increase the safety characteristics of material storage and dispensing vessels, with respect to the occurrence of leakage events.